Field of Invention
The present invention relates to a photosensitive resin composition for a color filter of a liquid crystal display (LCD) and a color filter produced by using the same. More particularly, the present invention relates to a photosensitive resin composition for a color filter with excellent linearity of a finer pattern and resistance to an alkaline solution.
Description of Related Art
At present, a color filter has been widely used in the application fields of a color liquid crystal display (LCD), a color fax machine, a color video camera and the like. With the increasing market requirements of office equipments such as the color LCD and the like, the method of producing the color filter is tended to be diverse, and methods such as a dyeing method, a printing method, an electrodeposition method, a dispersing method and the like have been developed. Now, the dispersing method is the major technique for producing the color filter.
In the aforementioned dispersing method, the pigment is dispersed in the photosensitive resin composition. Then, the photosensitive resin is coated on a glass substrate, followed by being exposed, developed and obtaining a specific pattern. Next, the aforementioned coating, exposing, and developing steps are repeated in three times, resulting in the desired red (R), green (G) and blue (B) pixel color patterns in the pixel color layer of the color filter. Typically, for further improving the contrast of the color filter, a light-shielding layer (or called a black matrix) is disposed between the pixel color layers that are formed by pixels.
In the process of the dispersing method, examples for the alkali-soluble resin of the photosensitive resin composition can be a copolymer polymerized by (meth)acrylic acid as a monomer component. The aforementioned photosensitive resin composition can be referred to related references of Japanese Patent Laid-Open Publications JP H06-95211, JP H08-183819, JP H09-311210 and so on.
However, with minimization and lightweight of a personal digital assistant and a digital camera in recent years, the color filter must be much thinner and higher color saturation. Thus, it's needed to increase the concentration of the colorant of the photosensitive resin composition. When the concentration of the colorant is increased, the amount of the resin in the photosensitive resin is reduced relatively. When the amount of the adhesive resin is reduced, the adhesives between the pixel and the shielding layer is reduced and the pixel is easily peeled off, resulting in destructing the linearity of the finer pattern.
Japanese Patent Laid-Open Publication No. 2001-075273 discloses a photosensitive resin composition. The polymer, which is copolymerized by a unsaturated monomer having a carboxylic group and a monomer having an epoxy group, serves as the alkali-soluble resin of the photosensitive resin, for improving the aforementioned problems of the linearity of the finer pattern. However, such photosensitive resin composition has defects of bad resistance to an alkaline solution.
Therefore, there is a need to improve the problems of the bad linearity of the finer pattern of the photosensitive resin and the bad resistance to an alkaline solution simultaneously, which are also the issues being solved urgently by the skilled person in this art, so as to meet the requirements of the industry field.